This Recommended Practice, Operational Definitions of Driving Performance Measures and Statistics, provides functional definitions of and guidance for performance measures and statistics concerned with driving on roadways. As a consequence, measurements and statistics will be calculated and reported in a consistent manner in SAE and ISO standards, journal articles proceedings papers, technical reports, and presentations so that the procedures and results can be more readily compared. Only measures and statistics pertaining to driver/vehicle responses that affect the lateral and longitudinal positioning of a road vehicle are currently provided in this document. Measures and statistics covering other aspects of driving performance may be included in future editions. For eye glance-related measures and statistics, see SAE J2396 (Society of Automotive Engineers, 2007) and ISO 15007-1 (International Standards Organization, 2002).
A common and consistently defined vocabulary is a basic requirement for comparing evaluation procedures and their results for driving contexts, vehicles, and vehicle components. This is the reason for foundational documents such as SAE J1100 Motor Vehicle Dimensions (Society of Automotive Engineers, 2009) and related mobility documents (Steinfeld, Fong, Kaber, Lewis, Scholtz, and Goodrich, 2006). (See also National Research Council, 2011.) As shown by Savino (2009) and Green (2012), many terms used to describe driving performance are not consistently named, defined (if they are defined at all), or used in the automotive engineering and research literature. This inconsistency makes comparing studies, test procedures, and results difficult, which in turn can compromise safety and usability. To overcome the inconsistency problem, this document provides standard names and definitions of driving performance measures and statistics, as well as supporting information to encourage their use.